Abundance and Distribution of Indian Mackerel ( Rastrelliger kanagurta ) along the South-West Coast of India in Respect to the Hydro-Biological Changes

Data on spatio-temporal distribution studies of the Indian mackerel (Rastrelliger kanagurta), were collected along the south-west coast of India between 2004 and 2007, together with the hydrobiological data. Data were collected along the latitudes between 110 N and 160 N and longitude between 720 E and 750 E. High catches were observed at the depth of 30–50 m during the post-monsoon compared to pre-monsoon, whereas negligible catches were observed at the depth of 30–100 m during monsoon. Mackerel size ranged between 11.5–28.5cm, 15.5–34.0 cm, 11.0–28.0 cm and 15.0–28.0 cm in 2004, 2005, 2006 and 2007 respectively during post-monsoon. The primary productivity (PP) ranged from 0.38 to 9.8 mg m−3d−1, temperature ranged between 23.1 and 29.60 C and Chlorophyll a (Chl a) ranged from 1.2 to 9.8 mgm−3 in surface and various depths of the water column. Our findings showed that the distribution of the mackerel population significantly shifted northward during the post-monsoon season. Results revealed that the Indian mackerel were mainly influenced by PP and temperature.